unfortumately your understanding is right

though I don't know your particular situation, my experience (with many friends), going back china, you will regret in 1-2 yrs, and then you will try to come back.

So do not give up your I485 for your family and more important, for yourself. It is not that bad to find a good job in US, you need a lot of networking, and good luck. I will encourage you to try more.